In cranes of the said type, the load hook can usually be raised and lowered by means of a hoisting cable that runs from a crane jib and an associated hoisting winch, and in addition it can be moved in a horizontal plane by adjusting movable crane elements, which naturally allows combined movements in several axes to approach different points in the crane working area. For example, in the case of a tower crane, the tower together with the attached jib can be turned about a vertical axis with a slewing drive, and a trolley on the jib can be moved with a traversing trolley to move the load hook into the desired position. In case of a crane with a luffable telescopic jib, the jib can be luffed up or down and telescoped in or out to adjust the overhang of the load hook, whereby the turntable carrying the jib can be turned about a vertical axis to move the boom position together with the load hook into the desired position. Depending on the type of crane, corresponding movable crane elements are moved by these assigned drive units to move the load hook to the desired point in the crane working area.
On the one hand, it is known on construction sites to control the movable crane elements from the cab via the input means of the control unit in the cab, for example with a joystick, to control and operate the drives, moving the load hook to the desired location. The crane operator, with his experience and his good sense of judgement, estimates the path to be travelled and intuitively operates the drive units as necessary. Alternatively or additionally, it is also known on construction sites to operate the crane not from the cab but by means of radio remote control. In that case, the crane operator is on the construction site and follows the crane hook to the marked load, and when the hook reaches its target, he attaches the load and has it moved into the desired position. Controlling the drive units via input means of the radio remote control has the advantage that the crane operator is much closer to the crane hook to be moved, and when it approaches the load or the load placement area, he can see the load to be picked up or the spot where the load hook is to place the load, much more accurately, which enables him to control the drive units more sensitively. However, operating the remote control requires some practice, since depending on where the crane operator stands with the remote control in relation to the crane, the rotational axes of the joystick of the remote control can be skewed in relation to the actual axes of movement.
DE 10 2008 047 425 A1 describes a crane with a radio remote control, where it is determined by means of a distance meter whether the radio remote control is in a pre-defined ring around the crane, and the radio remote control should be blocked when it is outside that ring. This is to prevent the crane operator's feet being caught under the outriggers of the crane when it is lowered, or prevent him from standing too far away from the crane to watch the lowering of the feet closely enough. However, the above named problem remains unsolved, namely the inability to approach a load or a drop-off point with enough precision.
DE 10 2011 120 734 A1 also describes a crane that is controllable with a mobile remote control. It provides for a release function for the remote control with which the crane operator must assume a pre-defined and safe position to perform a certain crane movement with the remote control. For this purpose, several transponders are provided on the crane which release the remote control when the operator approaches at a certain distance. If, for example, the crane operator wants to extend the outriggers on the right side of the crane, he must take the remote control to a certain transponder on the crane or near it, which keeps the crane operator at a safe distance.
DE 10 2006 001 279 A1 describes a tower crane with a trolley movable on the jig whereby a transmitter/receiver on the trolley communicates on the one hand with a transponder fastened to the load and on the other hand with a transponder rigidly mounted at the construction site. Through communication with the first transponder, pendulum movements of the load in relation to the trolley can be determined, or if these movements stop, it can be determined that the load has been set down. Communication with the second transponder allows to determine the trolley position and thus the actual unloading of the load, such that the load torque applied upon the crane can be determined together with the known load weight. When a predetermined limit is exceeded, corresponding crane movements can be prevented. However, this also does not solve the above mentioned problem, namely to find a simple way to move the load hook to a certain location with precision.
The object of the present disclosure therefore is to provide an improved crane of the kind described above, which does not have the disadvantages of the state of the art and develops the crane advantageously. In particular to be simplified is the precise controlled approach of a load or of the load hook approaching a drop-off point.
According to the present disclosure, in one example, the object is achieved by means of a crane comprising a load hook; movable crane elements for raising or lowering the crane within a crane working area via operating of associated drive units; and a control unit with an input device, a mobile portable target signal transmitter, a positioning device, and a target controller, the control unit including computer-readable instructions stored on non-transitory memory for: controlling the drive units based on operator input received at the input device; variably positioning the mobile portable target signal transmitter within the crane working area; determining, via the positioning device, a current position of the target signal transmitter relative to the load hook and/or one of the movable crane elements; and automatically controlling the drive units via the target controller in response to a signal from the positioning device such that the load hook is automatically moved to the mobile target signal transmitter.
It is proposed to automate the approach of a load hook to a certain target point in the crane working area. The crane operator can predetermine a target point or a target point signal and trigger the automatic approach to this target point whereby the drive units of the crane no longer have to be manually operated or controlled by the crane operator, but are automatically steered by the crane control system. According to the present disclosure, the crane uses a mobile portable target signal transmitter that can be variably positioned in the crane working area, a positioning device for automatically determining the current position of the target signal transmitter relative to the load hook and/or a crane element, and a target controller for the automatic steering of drive units in response to a signal of the positioning means, such that the load hook is automatically moved to the mobile target signal transmitter. The automatic move of the target signal transmitter with the load hook can be fully automatic such that the crane performs the corresponding crane movements when the portable signal transmitter is moved, such that the load hook is following the mobile target signal transmitter like a dog, or the crane operator walking across the construction site with the target signal transmitter. Alternatively to such a fully automatic load hook control, the desired target position can also advantageously be approached semi-automatically, such that the crane operator has to release the movement before the crane control performs the movement of the load hook or automatically steers the drive units accordingly. The crane operator can walk to the desired target point with the portable target signal transmitter and then, for example by activating a switch or input device on the radio remote control, trigger the automated load hook movement while the crane operator does not have to manually control the individual drive units such as the slewing unit, the traversing trolley or the hoisting winch, with the joy stick or similar device, but the necessary drive movements are automatically controlled by the control unit.
In the further development of the present disclosure, the portable target signal transmitter can be integrated in the portable remote control or the portable control panel with which the crane operator can control the crane outside the crane's cab or control stand. This allows the crane operator to simply predetermine the target position or the target point signal by walking ahead of the load hook with the remote control or walk to the desired target point. Alternatively to such an integration in the mobile control panel, the system can be further developed in that the portable target signal transmitter can also be an external device such as a separate portable component, for example in the form of a necklace or a watch-like unit to be worn by the crane operator. Alternatively or additionally, the portable target signal transmitter can also be a unit directly attachable to the load with suitable fasteners such as magnets, clips or other such positively connectable fasteners, whereby the fasteners are preferably detachable and can be re-used at different target points, for example at load placement locations or on loads to be picked up. In each case, the portable target signal transmitter may be communicatively coupled to the portable control panel, such as via a network, via wireless transmission, or radio transmission.
In principle, the mobile target signal transmitter can be of variable design and communicate with the positioning means in variable ways. According to one example of the present disclosure, the portable target signal transmitter can be designed as a transponder or radio signal transmitter and communicate with the positioning means via radio data transmission. The transponder can be of passive mode, such that it transmits a certain answer signal only when it receives a signal from the positioning means. However, alternatively, the transponder can also be of active mode, and transmit a transponder signal to the positioning means of its own, i.e., without receiving a call signal.
When a transponder is used as a target signal transmitter, the positioning device can comprise a suitable transponder tracking arrangement for tracking the transponder. For example, such a transponder tracking arrangement can comprise several transmitting/receiving modules spaced apart from each other on the crane, in particular on a crane jib, to communicate with the transponder of the portable target signal transmitter, whereby an evaluation arrangement evaluates the received transponder signals with regard to certain signal characteristics to determine the position of the transponder relative to the transmitting/receiving modules. In particular, the said evaluation arrangement can determine a signal propagation delay, such as the time span from emitting a call signal to receiving a transponder reply signal, for the various transmitting and/or receiving modules on the crane, using these to determine the distance of the transponder from the various receiving modules and hence the position of the target signal transmitter relative to the crane. Alternatively or additionally, the transponder tracking arrangement or its evaluation arrangement can also use or consider a signal strength of the transponder signals received from the transponder of the target signal transmitter to determine the distance from the receiving modules on the crane and hence the position of the transponder.
The tracking arrangement can work like radio cell tracking as it is known with mobile telephones, where the signal communication is evaluated with several transmission/receiving units.
Alternatively or additionally to such transponder tracking, the target signal transmitter can also comprise a global positioning system (GPS) unit, in particular a GPS signal receiver which determines the current position of the target signal transmitter from a global satellite-based positioning system and transmits a corresponding position signal to the crane's positioning device. Advantageously, the crane's positioning device can also be equipped with such a GPS unit or a GPS signal receiver to determine the position of the crane or a crane element such as the crane base or trolley in the same coordinate system as the GPS position of the target signal transmitter, such that the relative position of the target signal transmitter and the crane can be determined from which the crane control can calculate the path to be followed and direct the drive units accordingly to move the load hook to the target signal transmitter position. In one example, the crane's positioning device itself may not have such a GPS signal receiver. If the GPS coordinates of the crane location are known, they can also be entered manually in the crane control or imported by it in a suitable manner.
Alternatively or additionally to such a GPS signal generator, the target signal transmitter can also provide an optical target signal, for example in the form of a light signal such as a light beam or in the form of an optical marker, for example in the form of a target ring structure. The positioning device provided on the crane may comprise a camera or other suitable optical sensors, to determine the position of the optical marker relative to the crane. From this determined relative position the automatic movement of the load hook to the target position may be automatically controlled and the drive units may be activated accordingly.
Alternatively or additionally to such a portable target signal transmitter, according to another aspect of the present disclosure, a target point can also be reached or an appropriate target point signal can also be provided by virtually presenting the crane travel area and the marking that can be provided for a certain place inside this area. According to the present disclosure, the crane can comprise a display arrangement for displaying a graphic presentation of the crane working area, whereby the display arrangement is provided with a marking device to mark a target point to be reached in the graphic presentation, and a positioning device to determine the position of the marking relative to the load hook and/or another crane element, such that the target controller automatically steers the drive units subject to a signal from the positioning device, such that the load hook is automatically moved to the marked target point of the display or to the actual target point in the crane working area that corresponds to the marking in the display.
Advantageously, one such display arrangement can be provided in the radio remote control or mobile control panel of the crane, whereby the radio remote control of the control panel can advantageously comprise a touch display on which the crane working area can be displayed, for example, in the shape of the construction site, such that the crane operator, by touching a desired point on the display, can set the target point and generate the corresponding target point signal. Alternatively or additionally, such a display can, of course, also be provided in the crane's cab.
Below, the present disclosure is more closely described by means of example embodiments elaborated with reference to the figures.